Various systems have been suggested for defrosting the windshield of an aircraft, i.e. for removing frost after the frost has formed on the windshield. Large planes, commercial aircraft, jet aircraft and military helicopters are equipped with very extensive heating, defogging and air conditioning systems for the cabin, whether in flight or on the ground. Multi-engine, piston powered airplanes have auxiliary gas powered heaters which are usually ignited immediately after the engines are started. Such heaters include a combustion chamber, a heat exchange system and a battery-powered blower. Soon after being ignited, the auxiliary heater begins delivering heat to the cabin including the windshield's defrosting system without the need for aircraft motion or ram effect.
Small piston powered, single engine aircraft, however, are normally equipped with simple systems which, when in flight, take in outside air and the ram speed of the aircraft pushes the ambient air past a portion of the aircraft's exhaust system where it is heated and then through ducts into the cabin. Unfortunately, when such an aircraft is not in flight, there is virtually no ram air pushing through the heating system. Such systems also require sufficient heat from the engine. Also, some single engine, piston driven aircraft have no defrost provisions. This can create serious visibility problems in cold, wintry conditions, particularly in northern climates such as those found in Canada or the northern United States. During pre-flight preparations, engine start up, warm up, taxiing, and takeoff prior to flight, the cabin is not usually heated or is heated insufficiently by existing heating systems to defrost the windshield. During cold months, this can cause a very serious problem since the pilot's visibility of the outside can be poor because of fogging windows. During taxi and takeoff, this can lead to serious accidents.
Systems have been suggested for enhancing the heat supply to the defrosting systems for small aircrafts. For example, the present inventor disclosed a blower assisted heating and defogging system for small aircraft in U.S. Pat. No. 7,017,828 which utilizes heated air from a muffler shroud to heat external air drawn from outside the aircraft with the blower.
Thus, various systems have addressed the issue of clearing frost from a windshield, but have not addressed the problem of fogging windshields by impeding moist exhaled air from reaching a windshield and thereby preventing frost from forming on the windshield in the first instance.